A molecular sieve having an AFX framework was first synthesised as an aluminosilicate using diquaternary ammonium compounds, such as diDABCO-C4 or diQUIN-C4 (quinuclidine) as structure-directing agents (S. I. Zones, U.S. Pat. No. 4,508,837, 1985. M. E. Davis, R. F. Lobo, Chem. Mater., 1992, 4, 756-768. R. F. Lobo, S. I. Zones, M. E. Davis, J. Inclus. Phenom., 1995, 21, 47-48. R. F. Lobo, Chem. Mater., 1996, 8, 2409-2411). The silicoaluminophosphate version of AFX (SAPO-56) was reported to form using N,N,N′,N′-tetra-methyl-hexane-1,6-diamine (S. T. Wilson, R. W. Broach, C. S. Blackwell, C. A. Bateman, N. K. McGuire, R. M. Kirchner, Microporous Mesoporous Mater., 1999, 28, 125-137), and α,ω-bis(N-methylpyrrolidinium)alkane (M. J. Maple, C. D. Williams, Dalton Trans., 2007, 4175-4181). Recently, SAPO-56 was prepared by aminothermal synthesis containing triethylamine and trimethylamine in the synthesis (D. Wang, M. Yang, W. Zhang, D. Fan, P. Tian, Z. Liu, Cryst Eng Comm. 2016, 18, 1000-1008).
In typical synthesis techniques, molecular sieve crystals precipitate from a reaction mixture which contains the framework reactants (e.g., a source of silica, a source of alumina and a source of hydroxide ions for aluminosilicates; or (a source of silica, a source of alumina and a source phosphate for SAPOs), and an SDA. Such synthesis techniques usually take several days (depending on factors such as crystallization temperature) to achieve the desired crystallization. When crystallization is complete, the solid precipitate containing the zeolite crystals is separated from the mother liquor which is discarded. This discarded mother liquor contains unused SDA, which is often degraded due to harsh reaction conditions, and unreacted silica.
There is a need to develop new methods to produce molecular sieves that can be performed more economically, and more efficiently. One of the ways to accomplish this can be through the use of different SDAs.